Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

[InstCombine] Fold Ext(i1) Pred shr(A, BW - 1) => i1 Pred A s< 0 #68244

Merged
merged 2 commits into from
Oct 13, 2023
Merged

[InstCombine] Fold Ext(i1) Pred shr(A, BW - 1) => i1 Pred A s< 0 #68244

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
724778b
[InstCombine] Tests for the fold A < 0 Pred i1
XChy Oct 4, 2023
6832674
[InstCombine] Fold A >> BW-1 Pred Ext(i1) into A < 0 Pred i1
XChy Oct 3, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
56 changes: 27 additions & 29 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5382,35 +5382,6 @@ Instruction *InstCombinerImpl::foldICmpEquality(ICmpInst &I) {
return new ICmpInst(Pred, A, Builder.CreateTrunc(B, A->getType()));
}

// Test if 2 values have different or same signbits:
// (X u>> BitWidth - 1) == zext (Y s> -1) --> (X ^ Y) < 0
// (X u>> BitWidth - 1) != zext (Y s> -1) --> (X ^ Y) > -1
// (X s>> BitWidth - 1) == sext (Y s> -1) --> (X ^ Y) < 0
// (X s>> BitWidth - 1) != sext (Y s> -1) --> (X ^ Y) > -1
Instruction *ExtI;
if (match(Op1, m_CombineAnd(m_Instruction(ExtI), m_ZExtOrSExt(m_Value(A)))) &&
(Op0->hasOneUse() || Op1->hasOneUse())) {
unsigned OpWidth = Op0->getType()->getScalarSizeInBits();
Instruction *ShiftI;
Value *X, *Y;
ICmpInst::Predicate Pred2;
if (match(Op0, m_CombineAnd(m_Instruction(ShiftI),
m_Shr(m_Value(X),
m_SpecificIntAllowUndef(OpWidth - 1)))) &&
match(A, m_ICmp(Pred2, m_Value(Y), m_AllOnes())) &&
Pred2 == ICmpInst::ICMP_SGT && X->getType() == Y->getType()) {
unsigned ExtOpc = ExtI->getOpcode();
unsigned ShiftOpc = ShiftI->getOpcode();
if ((ExtOpc == Instruction::ZExt && ShiftOpc == Instruction::LShr) ||
(ExtOpc == Instruction::SExt && ShiftOpc == Instruction::AShr)) {
Value *Xor = Builder.CreateXor(X, Y, "xor.signbits");
Value *R = (Pred == ICmpInst::ICMP_EQ) ? Builder.CreateIsNeg(Xor)
: Builder.CreateIsNotNeg(Xor);
return replaceInstUsesWith(I, R);
}
}
}

// (A >> C) == (B >> C) --> (A^B) u< (1 << C)
// For lshr and ashr pairs.
const APInt *AP1, *AP2;
Expand Down Expand Up @@ -7186,6 +7157,33 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
if (Instruction *R = processUMulZExtIdiom(I, Op1, Op0, *this))
return R;
}

Value *X, *Y;
// Signbit test folds
// Fold (X u>> BitWidth - 1 Pred ZExt(i1)) --> X s< 0 Pred i1
// Fold (X s>> BitWidth - 1 Pred SExt(i1)) --> X s< 0 Pred i1
Instruction *ExtI;
if ((I.isUnsigned() || I.isEquality()) &&
match(Op1,
m_CombineAnd(m_Instruction(ExtI), m_ZExtOrSExt(m_Value(Y)))) &&
Y->getType()->getScalarSizeInBits() == 1 &&
(Op0->hasOneUse() || Op1->hasOneUse())) {
unsigned OpWidth = Op0->getType()->getScalarSizeInBits();
Instruction *ShiftI;
if (match(Op0, m_CombineAnd(m_Instruction(ShiftI),
m_Shr(m_Value(X), m_SpecificIntAllowUndef(
OpWidth - 1))))) {
unsigned ExtOpc = ExtI->getOpcode();
unsigned ShiftOpc = ShiftI->getOpcode();
if ((ExtOpc == Instruction::ZExt && ShiftOpc == Instruction::LShr) ||
(ExtOpc == Instruction::SExt && ShiftOpc == Instruction::AShr)) {
Value *SLTZero =
Builder.CreateICmpSLT(X, Constant::getNullValue(X->getType()));
Value *Cmp = Builder.CreateICmp(Pred, SLTZero, Y, I.getName());
return replaceInstUsesWith(I, Cmp);
}
}
}
nikic marked this conversation as resolved.
Show resolved Hide resolved
}

if (Instruction *Res = foldICmpEquality(I))
Expand Down
161 changes: 118 additions & 43 deletions llvm/test/Transforms/InstCombine/icmp-shr.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1302,9 +1302,9 @@ define i1 @lshr_neg_sgt_zero(i8 %x) {

define i1 @exactly_one_set_signbit(i8 %x, i8 %y) {
; CHECK-LABEL: @exactly_one_set_signbit(
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp slt i8 [[XOR_SIGNBITS]], 0
; CHECK-NEXT: ret i1 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i8 [[TMP1]], 0
; CHECK-NEXT: ret i1 [[TMP2]]
;
%xsign = lshr i8 %x, 7
%ypos = icmp sgt i8 %y, -1
Expand All @@ -1317,9 +1317,9 @@ define i1 @exactly_one_set_signbit_use1(i8 %x, i8 %y) {
; CHECK-LABEL: @exactly_one_set_signbit_use1(
; CHECK-NEXT: [[XSIGN:%.*]] = lshr i8 [[X:%.*]], 7
; CHECK-NEXT: call void @use(i8 [[XSIGN]])
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp slt i8 [[XOR_SIGNBITS]], 0
; CHECK-NEXT: ret i1 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i8 [[TMP1]], 0
; CHECK-NEXT: ret i1 [[TMP2]]
;
%xsign = lshr i8 %x, 7
call void @use(i8 %xsign)
Expand All @@ -1331,9 +1331,9 @@ define i1 @exactly_one_set_signbit_use1(i8 %x, i8 %y) {

define <2 x i1> @same_signbit(<2 x i8> %x, <2 x i8> %y) {
; CHECK-LABEL: @same_signbit(
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt <2 x i8> [[XOR_SIGNBITS]], <i8 -1, i8 -1>
; CHECK-NEXT: ret <2 x i1> [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = xor <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R1:%.*]] = icmp sgt <2 x i8> [[TMP1]], <i8 -1, i8 -1>
; CHECK-NEXT: ret <2 x i1> [[R1]]
;
%xsign = lshr <2 x i8> %x, <i8 7, i8 7>
%ypos = icmp sgt <2 x i8> %y, <i8 -1, i8 -1>
Expand All @@ -1347,9 +1347,9 @@ define i1 @same_signbit_use2(i8 %x, i8 %y) {
; CHECK-NEXT: [[YPOS:%.*]] = icmp sgt i8 [[Y:%.*]], -1
; CHECK-NEXT: [[YPOSZ:%.*]] = zext i1 [[YPOS]] to i8
; CHECK-NEXT: call void @use(i8 [[YPOSZ]])
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor i8 [[X:%.*]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt i8 [[XOR_SIGNBITS]], -1
; CHECK-NEXT: ret i1 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X:%.*]], [[Y]]
; CHECK-NEXT: [[R1:%.*]] = icmp sgt i8 [[TMP1]], -1
; CHECK-NEXT: ret i1 [[R1]]
;
%xsign = lshr i8 %x, 7
%ypos = icmp sgt i8 %y, -1
Expand Down Expand Up @@ -1382,9 +1382,10 @@ define i1 @same_signbit_use3(i8 %x, i8 %y) {

define <2 x i1> @same_signbit_poison_elts(<2 x i8> %x, <2 x i8> %y) {
; CHECK-LABEL: @same_signbit_poison_elts(
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt <2 x i8> [[XOR_SIGNBITS]], <i8 -1, i8 -1>
; CHECK-NEXT: ret <2 x i1> [[R]]
; CHECK-NEXT: [[YPOS:%.*]] = icmp sgt <2 x i8> [[Y:%.*]], <i8 -1, i8 poison>
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt <2 x i8> [[X:%.*]], zeroinitializer
; CHECK-NEXT: [[R1:%.*]] = xor <2 x i1> [[TMP1]], [[YPOS]]
; CHECK-NEXT: ret <2 x i1> [[R1]]
;
%xsign = lshr <2 x i8> %x, <i8 7, i8 poison>
%ypos = icmp sgt <2 x i8> %y, <i8 -1, i8 poison>
Expand All @@ -1397,11 +1398,10 @@ define <2 x i1> @same_signbit_poison_elts(<2 x i8> %x, <2 x i8> %y) {

define i1 @same_signbit_wrong_type(i8 %x, i32 %y) {
; CHECK-LABEL: @same_signbit_wrong_type(
; CHECK-NEXT: [[XSIGN:%.*]] = lshr i8 [[X:%.*]], 7
; CHECK-NEXT: [[YPOS:%.*]] = icmp sgt i32 [[Y:%.*]], -1
; CHECK-NEXT: [[YPOSZ:%.*]] = zext i1 [[YPOS]] to i8
; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[XSIGN]], [[YPOSZ]]
; CHECK-NEXT: ret i1 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i8 [[X:%.*]], 0
; CHECK-NEXT: [[R1:%.*]] = xor i1 [[TMP1]], [[YPOS]]
; CHECK-NEXT: ret i1 [[R1]]
;
%xsign = lshr i8 %x, 7
%ypos = icmp sgt i32 %y, -1
Expand Down Expand Up @@ -1450,11 +1450,9 @@ define i1 @exactly_one_set_signbit_wrong_shr(i8 %x, i8 %y) {

define i1 @exactly_one_set_signbit_wrong_pred(i8 %x, i8 %y) {
; CHECK-LABEL: @exactly_one_set_signbit_wrong_pred(
; CHECK-NEXT: [[XSIGN:%.*]] = lshr i8 [[X:%.*]], 7
; CHECK-NEXT: [[YPOS:%.*]] = icmp sgt i8 [[Y:%.*]], -1
; CHECK-NEXT: [[YPOSZ:%.*]] = zext i1 [[YPOS]] to i8
; CHECK-NEXT: [[R:%.*]] = icmp ugt i8 [[XSIGN]], [[YPOSZ]]
; CHECK-NEXT: ret i1 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = and i8 [[Y:%.*]], [[X:%.*]]
; CHECK-NEXT: [[R1:%.*]] = icmp slt i8 [[TMP1]], 0
; CHECK-NEXT: ret i1 [[R1]]
;
%xsign = lshr i8 %x, 7
%ypos = icmp sgt i8 %y, -1
Expand All @@ -1465,9 +1463,9 @@ define i1 @exactly_one_set_signbit_wrong_pred(i8 %x, i8 %y) {

define i1 @exactly_one_set_signbit_signed(i8 %x, i8 %y) {
; CHECK-LABEL: @exactly_one_set_signbit_signed(
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp slt i8 [[XOR_SIGNBITS]], 0
; CHECK-NEXT: ret i1 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i8 [[TMP1]], 0
; CHECK-NEXT: ret i1 [[TMP2]]
;
%xsign = ashr i8 %x, 7
%ypos = icmp sgt i8 %y, -1
Expand All @@ -1480,9 +1478,9 @@ define i1 @exactly_one_set_signbit_use1_signed(i8 %x, i8 %y) {
; CHECK-LABEL: @exactly_one_set_signbit_use1_signed(
; CHECK-NEXT: [[XSIGN:%.*]] = ashr i8 [[X:%.*]], 7
; CHECK-NEXT: call void @use(i8 [[XSIGN]])
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp slt i8 [[XOR_SIGNBITS]], 0
; CHECK-NEXT: ret i1 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i8 [[TMP1]], 0
; CHECK-NEXT: ret i1 [[TMP2]]
;
%xsign = ashr i8 %x, 7
call void @use(i8 %xsign)
Expand All @@ -1494,9 +1492,9 @@ define i1 @exactly_one_set_signbit_use1_signed(i8 %x, i8 %y) {

define <2 x i1> @same_signbit_signed(<2 x i8> %x, <2 x i8> %y) {
; CHECK-LABEL: @same_signbit_signed(
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt <2 x i8> [[XOR_SIGNBITS]], <i8 -1, i8 -1>
; CHECK-NEXT: ret <2 x i1> [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = xor <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R1:%.*]] = icmp sgt <2 x i8> [[TMP1]], <i8 -1, i8 -1>
; CHECK-NEXT: ret <2 x i1> [[R1]]
;
%xsign = ashr <2 x i8> %x, <i8 7, i8 7>
%ypos = icmp sgt <2 x i8> %y, <i8 -1, i8 -1>
Expand All @@ -1510,9 +1508,9 @@ define i1 @same_signbit_use2_signed(i8 %x, i8 %y) {
; CHECK-NEXT: [[YPOS:%.*]] = icmp sgt i8 [[Y:%.*]], -1
; CHECK-NEXT: [[YPOSZ:%.*]] = sext i1 [[YPOS]] to i8
; CHECK-NEXT: call void @use(i8 [[YPOSZ]])
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor i8 [[X:%.*]], [[Y]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt i8 [[XOR_SIGNBITS]], -1
; CHECK-NEXT: ret i1 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = xor i8 [[X:%.*]], [[Y]]
; CHECK-NEXT: [[R1:%.*]] = icmp sgt i8 [[TMP1]], -1
; CHECK-NEXT: ret i1 [[R1]]
;
%xsign = ashr i8 %x, 7
%ypos = icmp sgt i8 %y, -1
Expand Down Expand Up @@ -1545,9 +1543,10 @@ define i1 @same_signbit_use3_signed(i8 %x, i8 %y) {

define <2 x i1> @same_signbit_poison_elts_signed(<2 x i8> %x, <2 x i8> %y) {
; CHECK-LABEL: @same_signbit_poison_elts_signed(
; CHECK-NEXT: [[XOR_SIGNBITS:%.*]] = xor <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[R:%.*]] = icmp sgt <2 x i8> [[XOR_SIGNBITS]], <i8 -1, i8 -1>
; CHECK-NEXT: ret <2 x i1> [[R]]
; CHECK-NEXT: [[YPOS:%.*]] = icmp sgt <2 x i8> [[Y:%.*]], <i8 -1, i8 poison>
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt <2 x i8> [[X:%.*]], zeroinitializer
; CHECK-NEXT: [[R1:%.*]] = xor <2 x i1> [[TMP1]], [[YPOS]]
; CHECK-NEXT: ret <2 x i1> [[R1]]
;
%xsign = ashr <2 x i8> %x, <i8 7, i8 poison>
%ypos = icmp sgt <2 x i8> %y, <i8 -1, i8 poison>
Expand All @@ -1560,11 +1559,10 @@ define <2 x i1> @same_signbit_poison_elts_signed(<2 x i8> %x, <2 x i8> %y) {

define i1 @same_signbit_wrong_type_signed(i8 %x, i32 %y) {
; CHECK-LABEL: @same_signbit_wrong_type_signed(
; CHECK-NEXT: [[XSIGN:%.*]] = ashr i8 [[X:%.*]], 7
; CHECK-NEXT: [[YPOS:%.*]] = icmp sgt i32 [[Y:%.*]], -1
; CHECK-NEXT: [[YPOSZ:%.*]] = sext i1 [[YPOS]] to i8
; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[XSIGN]], [[YPOSZ]]
; CHECK-NEXT: ret i1 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i8 [[X:%.*]], 0
; CHECK-NEXT: [[R1:%.*]] = xor i1 [[TMP1]], [[YPOS]]
; CHECK-NEXT: ret i1 [[R1]]
;
%xsign = ashr i8 %x, 7
%ypos = icmp sgt i32 %y, -1
Expand All @@ -1589,3 +1587,80 @@ define i1 @exactly_one_set_signbit_wrong_shamt_signed(i8 %x, i8 %y) {
%r = icmp eq i8 %xsign, %yposz
ret i1 %r
}

define i1 @slt_zero_ult_i1(i32 %a, i1 %b) {
; CHECK-LABEL: @slt_zero_ult_i1(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 [[A:%.*]], 0
; CHECK-NEXT: [[TMP2:%.*]] = xor i1 [[B:%.*]], true
; CHECK-NEXT: [[CMP21:%.*]] = and i1 [[TMP1]], [[TMP2]]
; CHECK-NEXT: ret i1 [[CMP21]]
;
%conv = zext i1 %b to i32
%cmp1 = lshr i32 %a, 31
%cmp2 = icmp ult i32 %conv, %cmp1
ret i1 %cmp2
}

define i1 @slt_zero_ult_i1_fail1(i32 %a, i1 %b) {
; CHECK-LABEL: @slt_zero_ult_i1_fail1(
; CHECK-NEXT: [[CONV:%.*]] = zext i1 [[B:%.*]] to i32
; CHECK-NEXT: [[CMP1:%.*]] = lshr i32 [[A:%.*]], 30
; CHECK-NEXT: [[CMP2:%.*]] = icmp ugt i32 [[CMP1]], [[CONV]]
; CHECK-NEXT: ret i1 [[CMP2]]
;
%conv = zext i1 %b to i32
%cmp1 = lshr i32 %a, 30
%cmp2 = icmp ult i32 %conv, %cmp1
ret i1 %cmp2
}

define i1 @slt_zero_ult_i1_fail2(i32 %a, i1 %b) {
; CHECK-LABEL: @slt_zero_ult_i1_fail2(
; CHECK-NEXT: [[CONV:%.*]] = zext i1 [[B:%.*]] to i32
; CHECK-NEXT: [[CMP1:%.*]] = ashr i32 [[A:%.*]], 31
; CHECK-NEXT: [[CMP2:%.*]] = icmp ugt i32 [[CMP1]], [[CONV]]
; CHECK-NEXT: ret i1 [[CMP2]]
;
%conv = zext i1 %b to i32
%cmp1 = ashr i32 %a, 31
%cmp2 = icmp ult i32 %conv, %cmp1
ret i1 %cmp2
}

define i1 @slt_zero_slt_i1_fail(i32 %a, i1 %b) {
; CHECK-LABEL: @slt_zero_slt_i1_fail(
; CHECK-NEXT: [[TMP1:%.*]] = icmp slt i32 [[A:%.*]], 0
; CHECK-NEXT: [[TMP2:%.*]] = xor i1 [[B:%.*]], true
; CHECK-NEXT: [[CMP21:%.*]] = and i1 [[TMP1]], [[TMP2]]
; CHECK-NEXT: ret i1 [[CMP21]]
;
%conv = zext i1 %b to i32
%cmp1 = lshr i32 %a, 31
%cmp2 = icmp slt i32 %conv, %cmp1
ret i1 %cmp2
}

define i1 @slt_zero_eq_i1_signed(i32 %a, i1 %b) {
; CHECK-LABEL: @slt_zero_eq_i1_signed(
; CHECK-NEXT: [[TMP1:%.*]] = icmp sgt i32 [[A:%.*]], -1
; CHECK-NEXT: [[CMP21:%.*]] = xor i1 [[TMP1]], [[B:%.*]]
; CHECK-NEXT: ret i1 [[CMP21]]
;
%conv = sext i1 %b to i32
%cmp1 = ashr i32 %a, 31
%cmp2 = icmp eq i32 %conv, %cmp1
ret i1 %cmp2
}

define i1 @slt_zero_eq_i1_fail_signed(i32 %a, i1 %b) {
; CHECK-LABEL: @slt_zero_eq_i1_fail_signed(
; CHECK-NEXT: [[CONV:%.*]] = sext i1 [[B:%.*]] to i32
; CHECK-NEXT: [[CMP1:%.*]] = lshr i32 [[A:%.*]], 31
; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i32 [[CMP1]], [[CONV]]
; CHECK-NEXT: ret i1 [[CMP2]]
;
%conv = sext i1 %b to i32
%cmp1 = lshr i32 %a, 31
%cmp2 = icmp eq i32 %conv, %cmp1
ret i1 %cmp2
}
Loading
Loading